Apparatus, system, and method for providing energy management, profiles, and message blocks in a cable service environment

ABSTRACT

A method is provided in one example and includes creating a plurality of profiles that describe one or more downstream modulations for each data-subcarrier in a channel to be used by a plurality of cable modems; receiving at least one testing measurement from the plurality of cable modems; and assigning a selected one of the plurality of profiles to each of the plurality of cable modems based, at least in part, on the one testing measurement that was received.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority under 35 U.S.C. §119(e)to U.S. Provisional Application Ser. No. 61/724,688, “MULTI-CHANNELDOWNSTREAM ARCHITECTURE” filed on Nov. 9, 2012, 61/729,186,“MULTI-CHANNEL DOWNSTREAM ARCHITECTURE” filed on Nov. 21, 2012, and61/769,244 “MULTI-CHANNEL DOWNSTREAM ARCHITECTURE” filed on Feb. 26,2013, all of which are hereby incorporated by reference in theirentirety.

TECHNICAL FIELD

This disclosure relates in general to the field of communications and,more particularly, to an apparatus, a system, and a method for providingenergy management, profiles, and message blocks in a cable serviceenvironment.

BACKGROUND

Data Over Cable Service Interface Specification (DOCSIS) is aninternational telecommunications standard that permits the addition ofhigh-speed data transfer to an existing cable TV (CATV) system. DOCSIScan be employed by cable television operators to provide Internet accessover their existing hybrid fiber-coaxial (HFC) infrastructure. DOCSIScan provide a variety in options available at Open SystemsInterconnection (OSI) layers 1 and 2, the physical, and data linklayers. As with any system that serves consumers, optimizing speed,latency, processing time, synchronization, etc. presents a significantchallenge to system designers, network architects, and engineers alike.

BRIEF DESCRIPTION OF THE DRAWINGS

To provide a more complete understanding of the present disclosure andfeatures and advantages thereof, reference is made to the followingdescription, taken in conjunction with the accompanying figures, whereinlike reference numerals represent like parts, in which:

FIG. 1 is a simplified block diagram of a communication systemassociated with a hybrid fiber-coaxial (HFC) infrastructure inaccordance with one embodiment of the present disclosure;

FIG. 2 is a simplified block diagram of a communication systemassociated with traffic propagating through a data-over-cable system inaccordance with one embodiment of the present disclosure;

FIG. 3 is a simplified block diagram illustrating a plurality of modulesto be used in the communication system in accordance with one embodimentof the present disclosure;

FIG. 4 is a simplified block diagram illustrating a potential cloudnetwork environment in accordance with one embodiment of the presentdisclosure;

FIG. 5 is a simplified block diagram illustrating a plurality of planesin accordance with one embodiment of the present disclosure;

FIG. 6 illustrates an example graph associated with subcarriers inaccordance with one embodiment of the present disclosure;

FIG. 7 illustrates an example schematic associated with orthogonalfrequency-division multiplexing (OFDM) in accordance with one embodimentof the present disclosure;

FIG. 8 is a schematic diagram illustrating an example of a subcarrierassignment in accordance with one embodiment of the present disclosure;

FIG. 9 illustrates an example Forward Error Correction (FEC) blockdiagram in accordance with one example embodiment of the presentdisclosure;

FIG. 10 illustrates an example graph associated with downstream profilesin accordance with one embodiment of the present disclosure;

FIG. 11 illustrates an example table associated with codeword builderlatency in accordance with one embodiment of the present disclosure;

FIG. 12 is a simplified block diagram that reflects a codeword andprofile relationship in accordance with one embodiment of the presentdisclosure;

FIG. 13 is a simplified block diagram that reflects one possibleconfiguration for the downstream (DS) framework in accordance with oneembodiment of the present disclosure;

FIG. 14 is a simplified block diagram that reflects one possible mappingconfiguration for mapping packets to FEC blocks in accordance with oneembodiment of the present disclosure;

FIG. 15 illustrates an example schematic associated with a plurality ofDOCSIS frames and the FEC in accordance with one embodiment of thepresent disclosure;

FIG. 16 illustrates an example schematic associated with time-frequencyscheduling in accordance with one embodiment of the present disclosure;

FIG. 17 illustrates an example schematic associated with OFDM channelcomponents in accordance with one embodiment of the present disclosure;

FIG. 18 illustrates an example schematic associated with an examplemessage block in accordance with one embodiment of the presentdisclosure;

FIGS. 19-20 illustrate example configurations and packet formattingassociated with an example PHY Link Channel (PLC) in accordance with oneembodiment of the present disclosure;

FIG. 21 illustrates an example schematic associated with a next codewordpointer (NCP) mapping in accordance with one embodiment of the presentdisclosure;

FIG. 22 illustrates an example schematic associated with an NCP messageblock in accordance with one embodiment of the present disclosure;

FIG. 23 illustrates an example schematic associated with a timestampmessage block in accordance with one embodiment of the presentdisclosure;

FIG. 24 illustrates an example formatting associated with an extendedtimestamp in accordance with one embodiment of the present disclosure;

FIG. 25 illustrates an example formatting associated with an energymanagement message block in accordance with one embodiment of thepresent disclosure;

FIG. 26 illustrates an example formatting associated with a messagechannel message block in accordance with one embodiment of the presentdisclosure;

FIG. 27 illustrates an example formatting associated with a nextcodeword pointer message block in accordance with one embodiment of thepresent disclosure;

FIG. 28 illustrates an example configuration associated with a LightSleep Group Mode in accordance with one embodiment of the presentdisclosure;

FIG. 29 illustrates an example formatting associated with an energymanagement (EM) duty cycle approach in accordance with one embodiment ofthe present disclosure;

FIG. 30 illustrates an example formatting associated with a duty cycleapproach for data channel in accordance with one embodiment of thepresent disclosure;

FIG. 31 illustrates an example formatting associated with an OFDMchannel descriptor in accordance with one embodiment of the presentdisclosure;

FIG. 32 illustrates an example formatting associated with a downstreamprofile descriptor in accordance with one embodiment of the presentdisclosure;

FIG. 33 is a table illustrating potential results and profilesassociated with multicast traffic in accordance with one embodiment ofthe present disclosure; and

FIG. 34 is a simplified block diagram illustrating one potential timingconfiguration associated with a cable modem termination system and acable modem in accordance with one embodiment of the present disclosure.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS Overview

A method is provided in one example and includes creating a plurality ofprofiles that describe one or more downstream modulations for eachdata-subcarrier in a channel to be used by a plurality of cable modems;receiving at least one testing measurement from the plurality of cablemodems; and assigning a selected one of the plurality of profiles toeach of the plurality of cable modems based, at least in part, on theone testing measurement that was received.

In more particular embodiments, the method can include executing analgorithm in order to sort the plurality of cable modems into a set ofgroups based on signal-to-noise ratio measurements received from each ofthe plurality of cable modems. Additionally, the plurality of profilesare managed by a cable modem termination system (CMTS). The method couldalso include adjusting at least a portion of an orthogonalfrequency-division multiplexing (OFDM) spectrum in a downstream pathbetween the CMTS and the plurality of cable modems. Packets to bepropagated to the plurality of cable modems can be placed into ForwardError Correction (FEC) codewords that have an associated one of theprofiles. In certain cases, a CMTS is configured to assign a particularPHY Link Channel (PLC) to each OFDM channel in a downstream path betweenthe CMTS and the plurality of cable modems.

Each of the plurality of cable modems can belong to multiple groups suchthat multiple transmission paths exist for each of the plurality ofcable modems. Each of the profiles can include a list of modulationorders that are defined for one or more subcarriers within an OFDMchannel. A CMTS can define the plurality of profiles for use in an OFDMchannel for a downstream path between the CMTS and the plurality ofcable modems. Each OFDM channel in a downstream path between the CMTSand the plurality of cable modems has its own unique set of profiles.Parameters that describe an OFDM downstream channel and each profile onthat OFDM downstream channel can be defined in OFDM Channel Descriptor(OCD) and Downstream Profile Descriptor (DPD) messages.

A number of profiles supported by a CMTS is based, at least in part, ona latency characteristic and an available bandwidth for a particularOFDM channel. At least one of the profiles is a common profile used by amajority of the plurality of the cable modems that can receive anddecode data. At least one of the profiles is used for communicatingmulticast MAC Management Message (MMMs). A DPD can be used by a CMTS tocommunicate parameters of the profiles to the plurality of cable modems.Multicast sessions can be propagated on a particular profile that iscommon to a multicast group associated with particular cable modems. ACMTS can indicate to a particular one of the plurality of cable modemsto test a particular profile. Results of the test for the particular oneof the cable modems is subsequently reported back to the CMTS such thatthe CMTS adds the particular profile to the particular one of theplurality of cable modems.

Example Embodiments

Turning to FIG. 1, FIG. 1 is a simplified block diagram of acommunication system 10 associated with a hybrid fiber-coaxial (HFC)infrastructure in accordance with one embodiment of the presentdisclosure. In one example embodiment, the framework of FIG. 1 canleverage orthogonal frequency-division multiplexing (OFDM) to customizea frequency profile to allow for optimum throughput. Such a profilecould, for example, use an optimal modulation order for each subcarrierand, further, mute subcarriers in situations where interference waspresent. In addition, Low Density Parity Check (LDPC) is an errorcorrection technology that effectively allows higher orders ofmodulation to be used by the framework of FIG. 1. In one general sense,this could allow for an “average” signal-to-noise ratio (SNR) to be usedfor setting modulation levels. Note that despite the higher degree offlexibility that OFDM provides, the HFC plant is relatively stable andreadily maintained, where the amount of variation among cable modems(CMs) can be minimized. Thus, a small number of profiles, such as fourfor example, may be sufficient to allow a compromise between systemoptimization and retaining a desired simplicity for the architecture, asfurther detailed below.

In at least one embodiment, the architecture of FIG. 1 can utilizedownstream profiles to adjust the OFDM spectrum for appropriatetransmission performance in the downstream path between a cable modemtermination system (CMTS) and a CM. The CMTS can execute an algorithm tosort CMs into a small set of groups based on SNR measurements receivedfrom the CMs. The profile management, algorithms, and implementation canbe executed on the CMTS, or a server, or at any other appropriatelocation in the network. A given CM may belong to multiple groups and,therefore, there can be multiple transmission paths to each CM. In oneexample embodiment, a given CMTS can tell the CM to test a particularprofile. The CM can subsequently report back to the CMTS if the testpasses. If the result of the test is positive, then the CMTS can addthat profile to the CM. Hence, in at least one sense, there is adistributed system that can be used to test, validate, and addparticular profiles.

Additionally, in certain embodiments of the present disclosure, CMs thatare receiving or sending traffic below a configurable threshold can beput into a low power mode (e.g., a DOCSIS Light Sleep Mode (DLS)). Thiscan be achieved by segmenting the CMs into logical DLS groups.Instructions can be provided to each of the CMs in each group (orindividually) to shut down their receivers for a configurable period oftime. Once that time has lapsed, the CM can re-enable its PHY, rejointhe network, and look for a message to indicate whether it shouldreceive data or return to a power down mode.

Separately, the framework of FIG. 1 can provide for the generation ofmessage blocks. The downstream direction can use a separate channel forsending signaling messages to the CMs when they are booting up andbefore they connect to the network. The channel can also provide basicfeatures such as bootstrap parameters, timestamp, DLS messages, etc. Inat least one sense, a message block can be viewed as a building blockconcept. A Next Codeword Pointer (NCP) can be constructed using messageblocks, as further detailed below. There is also an update mechanism forthe NCP that can use the profiles. Before detailing each of thesefunctions (e.g., the message block, the energy/sleep mode capabilities,the downstream profile management, etc.), a brief overview ofcommunication system 10 of FIG. 1 is provided, along with some generalcontextual information associated with the potential problems andtechnologies being implicated by the present disclosure.

Returning to FIG. 1, FIG. 1 includes a network management system (NMS)12, a plurality of provisioning systems 14, and a CMTS 16, all of whichmay be suitably coupled to any type of network (e.g., an Internet, anIntranet, a wireless network, local area network (LAN), etc.). Alsoprovided in FIG. 1 is an HFC network 18, which is coupled to multipleCMs 20 a-20 b. Each CM can be coupled to various instances of customerpremise equipment (CPE) 15 a-15 d, which may be associated with InternetProtocol (IP) version 4 (IPv4) or version 6 (IPv6). FIG. 1 also includesat least one layer associated with a software defined networking (SDN)element 14, which may or may not cooperate with a cloud network 22 inaccordance with certain embodiments of the present disclosure.

In one example implementation, the CM can connect to the operator'scable network and to a home network, bridging packets between them. ManyCPE devices can connect to the CM's LAN interfaces. CPE devices can beembedded with the CM in a single device, or they can be separate,standalone devices. CPE devices may use IPv4, IPv6, or both forms of IPaddressing. Examples of typical CPE devices include home routers,set-top devices, personal computers, etc. The CMTS connects theoperator's back office and core network with the cable network. Its mainfunction is to forward packets between these two domains, and betweenupstream and downstream channels on the cable network.

Various applications can be used in the back office to provideconfiguration and other support to the devices on the DOCSIS™ network.These applications can use IPv4 and/or IPv6, as appropriate to theparticular operator's deployment. The applications can includeprovisioning systems such as:

1) The Dynamic Host Configuration Protocol (DHCP) servers provide the CMwith initial configuration information, including IP address(es), whenthe CM boots.

2) The Config File server is used to download configuration files to CMswhen they boot. Configuration files are in binary format and permit theconfiguration of the CM's parameters.

3) The Software Download server is used to download software upgrades tothe CM.

4) The Time Protocol server provides Time Protocol clients, typicallyCMs, with the current time of day.

5) Certificate Revocation server provides certificate status.

With respect to the NMS, a Simple Network Management Protocol (SNMP)Manager allows the operator to configure and monitor SNMP agents(typically, the CM and the CMTS). A Syslog server collects messagespertaining to the operation of devices.

FIG. 2 is a simplified block diagram of an example communication system30 associated with traffic propagating through the data-over-cablesystem in accordance with one embodiment of the present disclosure. FIG.2 includes a wide area network (WAN) 32, a CMTS 34, a cable network 36,a cable modem 38, and a CPE 40. The DOCSIS system allows transparentbi-directional transfer of IP traffic, between the cable system head-endand customer locations, over an all-coaxial or hybrid-fiber/coax (HFC)cable network.

FIG. 3 is a simplified block diagram illustrating one possibleconfiguration for achieving at least some of the functions discussedherein with respect to the sleep mode capabilities, the profilemanagement, the message block construction, etc. FIG. 3 includes CMTS16, which (in this particular non-limiting example) includes a processor44, a memory element 52, a profile management module 54, a sleep modemodule 56, and a message block module 58. Any of these functions andmodules may be provided elsewhere (e.g., in a server, in a cloudcomponent, in another device, etc.), or they can be consolidated in anysuitable fashion, or responsibilities can be shared by any one or moreof the CMs, along with CMTS 16.

FIG. 4 is a simplified block diagram that illustrates an example cloudconfiguration 45 that may be used in conjunction with the presentdisclosure. In the example of FIG. 4, a Converged Cable Access Platform(CCPA) application suite is provided, along with an SDN controller thatcan include any number of application program interfaces (APIs) as isbeing shown. Note that this particular example of FIG. 4 lists onlysome, of the many possible technologies and APIs that can be used inconjunction with the present disclosure. FIG. 5 illustrates onepotential logical representation 50 of a management plane, a servicesplane, a control plane, and a forwarding plane and, further, how suchplanes can be integrated and managed from the perspective of an IndustrySDN and an Industry Network Function Virtualization (NFV). In at leastone example, the present disclosure can use an alternative frameworkassociated with the alternative SDN and alternative NFV, as is beingillustrated by FIG. 5.

Note that in terms of the terminology discussed herein, the term‘channel’ can be used to refer to an OFDM channel, (e.g., a common FFTthat is typically 192 MHz). The term ‘template’ can refer to a list ofsub-carriers, their functions (data, pilot, guard, etc.), and locations.The term ‘slice’ can refer to a fraction of the downstream OFDM channelthat has a specific membership group of CMs. The term ‘profile’ caninclude any suitable list of modulations for each data-subcarrier in anOFDM channel. The Convergence Layer can be abbreviated CL and the CLcontrol channel (CLCC) can include the Next Profile Pointer (NPP), aTimestamp, and a Message Channel. Additionally, the MAC ManagementMessage can be abbreviated MMM.

The data channel can be comprised of data slices, where each slice caninclude a CM membership group. A CM may be a member of one or moreslices. The physical characteristics of the data sub-carriers used inthe OFDM channel can be provided in a profile. Each data slice canreference a profile in certain embodiments of the present disclosure.There may be more slices than profiles. Thus, more than one slice mayshare the same profile (e.g., a Light Sleep mode). The control channelcan be composed of message blocks. The control channel can include theNPP and any suitable timestamp. The control channel can include a CLmessage channel for select MAC Management Messages.

In terms of OFDM background, FIG. 6 illustrates a graph 60 associatedwith pilot subcarriers, data subcarriers, guard subcarriers, etc. As ageneral proposition, orthogonal frequency division multiplexing is alarge collection of narrow quadrature amplitude modulation (QAM)subcarriers. FIG. 7 illustrates an example schematic 70 associated withOFDM, where iFFT=inverse FFT, an iFFT converts from the frequency domainto the time domain, and an FFT converts from the time domain to thefrequency domain.

Cable networks have previously used frequency division multiplexing(FDM) to allow the transmission of several RF signals through the samelength of coaxial cable at the same time. Each RF signal is on aseparate frequency or, more specifically, assigned to its own channelslot. National Television System Committee (NTSC) analog TV signals eachoccupy six megahertz of bandwidth, and each six-megahertz-wide chunk ofspectrum is a channel. A color subcarrier is located in between thevisual and aural carriers, approximately 3.58 MHz above the visualcarrier. As the cable industry moved to digital transmission, themodulation of choice was QAM. Each downstream QAM signal occupies thesame six megahertz of bandwidth as an analog TV signal. The currentmethod of QAM transmission is known as single carrier QAM (SC-QAM); thelatter is true even when DOCSIS 3.0 channel bonding is used. Eachchannel slot carries only one modulated carrier (a QAM signal) hence,the SC-QAM moniker. The entire data payload transmitted in the channelmodulates just that one QAM signal.

Each of the narrow QAM signals, called a subcarrier, subchannel, ortone, carries a small percentage of the total payload at a low datarate. The aggregate of the subcarriers' data rates comprises the totaldata payload. This variation of FDM is known as OFDM. For improvedspectral efficiency, the subcarriers can overlap one another. Thissounds counterintuitive because if signals overlap each otherinterference can occur. With OFDM, the subcarriers are mathematicallyorthogonal to (i.e., distinguishable from) one another, which addressesthe interference concern. “Orthogonal” in this case simply refers to thesubcarriers being independent such that there is no interaction betweenthem despite the overlap in frequency. The concept is analogous tohaving zero inter-symbol interference (ISI) in the time domain.

Orthogonality can be achieved by spacing the subcarriers at thereciprocal of the symbol period (T), also called symbol duration time.This spacing results in the sin (sin x/x) frequency response curves ofthe subcarriers lining up so that the peak of one subcarrier's responsecurve falls on the first nulls of the lower and upper adjacentsubcarriers' response curves. Orthogonal subcarriers each have aninteger number of cycles in the interval T.

OFDM can be used for multiple access by assigning different subcarriersto different users. OFDM also can be used in combination with such othermultiple access schemes as time division multiple access (TDMA). In thiscase, the full channel would be assigned to one user at a time, and themultiple access achieved via time division. When combined with TDMA,OFDM can deliver a high peak-data rate, which may be desirable for someapplications.

Turning to FIG. 8, FIG. 8 is a schematic diagram 80 illustrating anexample of a subcarrier assignment. More specifically, this illustrationshows an OFDM channel with PLC after interleaving. The OFDM spectrum isillustrated in FIG. 8 and, further, described by two messages OFDMChannel Descriptor (OCD) and Downstream Profile Descriptor (DPD). On theleft is subcarrier(0), which is the first numbered subcarrier and istypically an excluded carrier. The outer 6.4 MHz past each end of the192 MHz maximum spectrum is excluded. There are fixed pilot tonesdescribed by OCD and DPD and scattered pilots are that algorithmicallydescribed and not described by OCD and DPD. The PLC starts somewhere inthe spectrum. There are data subcarriers that carry DOCSIS frames. Somesubcarriers are muted on a per-profile basis. There is also an NCPchannel that points to codeword locations. Although the NCP channel isshown at the top end of the spectrum, it is actually spread through thespectrum as it is frequency and time interleaved along with the datacarriers.

The OCD message generally assigns static functions like PLC usage,excluded subcarriers, and continuous pilots. Any subcarrier that has notbeen defined as an excluded subcarrier or a continuous pilot isconsidered as an active data subcarrier. The DPD message defines theactive data subcarriers with values such as muting and modulation. Thesevalues can change from one profile to another in accordance with theteachings of the present disclosure. The exception to this guideline isthat continuous pilots can be assigned with the DPD vector. The samelist/range type-length-value (TLV) structure can be used for thesubcarrier assignment in both the OCD and DPD messages, although theusage is different for each message. The DPD message also has analternate method of describing spectrum usage based upon a vectorstructure.

When the subcarrier assignment TLV is used in range mode, the length ofthe value field can be about 5 bytes. When the subcarrier assignment TLVis used as a list, the length is variable up to a maximum of 255 bytes.The number of list entries can be (length−1)/2. Thus, the maximum numberof list entries can be 127 entries. A range is defined by a startingsubcarrier index and an ending subcarrier index. The ending subcarrierindex can equal the beginning subcarrier index, but should not be less.

A continuous range can mean that the subcarrier assignment applies tosubcarriers within the specified range. A range with a skip value of onecan mean that one subcarrier is skipped and that every second subcarrierwould be assigned, beginning with the start subcarrier. The skip rangeis intended to be used to define mixed modulation profiles. Any suitablelist entry is one or more discrete subcarrier indexes. In certainembodiments, the CMTS can repeat the subcarrier assignment TLV as manytimes as necessary within the OCD message and within the DPD message tocomplete the description of the entire OFDM channel.

For default and specific values, the subcarrier assignment range/listTLV has a default mode. Subcarriers can be assigned a default value thatcan then subsequently be over-written with a specific value. Forexample, the subcarrier TLV could be issued once with active datasubcarriers set to a default modulation. The TLV could be issued againwith discrete active data subcarriers listed that might use a differentmodulation. This dual assignment can be unique within each of the OCDand DPD messages since OCD and DPD assign different functions todifferent subcarriers. The use of a default value and specific valueintroduces multiple assignment of a subcarrier. The use of two messagesalso introduces the possibility of multiple assignments. The followingrequirements remove all ambiguity.

In accordance with one example embodiment, the subcarrier assignmentsdefined by NCP and by scattered subcarriers have a higher precedencethan subcarrier assignments in the OCD and DPD messages. The CMTS canassign at least one “default” or “specific” function to each subcarrier.The CMTS should not assign more than one “default” function persubcarrier per message. The CMTS should not assign more than one“specific” function per subcarrier per message. The CM can give firstprecedence to “specific” assignments of subcarriers by the OCD message.The CM can give second precedence to “default” assignments ofsubcarriers by the OCD message. The CM can give third precedence to“specific” assignments of subcarriers by the DPD message. The CM cangive fourth precedence to “default” assignments of subcarriers by theDPD message. These provisions define TLV precedence explicitly and,thus, do not require TLVs to be transmitted in any defined order.

Subcarriers may also be assigned directly with a vector. A vector caninclude a starting subcarrier number and then a series of 4-bitmodulation assignments. Note that the length field of the SubcarrierAssignment Vector can be two bytes instead of one byte. When evaluatingrules, assignments by the vector TLV are considered “specific”assignments.

If the number of subcarriers described in the subcarrier assignmentvector is an odd number, then the CMTS can assert the odd bit identifierand use a value of zero in the four least significant bits of the lastbyte of the vector. If the subcarrier assignment vector can be set toodd, the CM can ignore the four least significant bits of the last byteof the vector. For the OCD operation, the location of the PLC channelcan be appropriately designated. This is typically done with one range.Excluded subcarriers can be identified. This is typically done with oneor more ranges. Discrete continuous pilots can be identified. This istypically done with one or more lists. (Alternatively, continuous pilotassignment can also be done in the DPD vector).

For the DPD operation, default modulation can be assigned to active datasubcarriers. This is typically done with one range and a defaultsetting. This step may be skipped in certain embodiments of the presentdisclosure. Specific modulation can be assigned to active datasubcarriers if they differ from the default. This is typically done withone or more ranges, one or more lists, or as part of a vector. Mutedsubcarriers can be assigned. This typically is done with one or moreranges, any suitable list, or as part of a vector, for example.

FIG. 9 illustrates an example Forward Error Correction (FEC) blockdiagram 90 in accordance with one example embodiment of the presentdisclosure. The FEC protocol adds redundant bits so that erred bits canbe recreated. FEC can use an interleaver in order to be effective. It ismore robust than Reed-Solomon and Bose Chaudhuri Hocquenghem (BCH) maybe used as an outer FEC in certain example embodiment. For FEC parity, afull codeword can be about 16,200 bits, in one example configuration ofthe present disclosure. A short codeword is acceptable and the codewordcan be 16-bit aligned with stuffing bits. For the FEC payload, this canbe similar to D3.0 frame mapping to MPEG-TS. A 2-byte header can includethe start of a packet pointer, where the data field is segmented DOCSISframes.

Turning to FIG. 10, FIG. 10 illustrates an example graph 100 associatedwith downstream profiles in accordance with one embodiment of thepresent disclosure. DOCSIS 3.1 can offer downstream profiles for OFDMchannels. A profile includes any suitable list of modulation orders thatare defined for each of the subcarriers within an OFDM channel, asdefined by the Downstream Profile Descriptor (DPD). The CMTS can alsodefine multiple profiles for use in an OFDM channel, where the profilescan differ in the modulation orders assigned to each subcarrier. TheCMTS can assign different profiles for different groups of CMs incertain embodiments of the present disclosure.

For convenience, each profile can be assigned a letter: Profile A,Profile B, and so forth. In this example, Profile A denotes the commonprofile that all CMs can receive and decode. A modem can use Profile Awhen it first initializes. Each OFDM channel has its own unique set ofprofiles. Thus, Profile A on OFDM channel 1 could be different fromProfile A on OFDM channel 2. In DOCSIS protocol encodings, ProfileIdentifier 0 is commonly referred to as Profile A. Profile Identifiers1, 2, and 3 are commonly referred to as Profiles B, C, and D,respectively.

Any profile can be used to send MMMs. The CMTS is responsible for makingsure that MMMs are transmitted on appropriate profiles such that a CMcan receive them. The CMTS can ensure that the CM does not receiveduplicate MMMs on a single OFDM channel. One way the CMTS can satisfythis requirement is to transmit broadcast and multicast MMMs on ProfileA. The parameters that describe the OFDM downstream channel and eachprofile on that channel are defined in OFDM Channel Descriptor (OCD) andDownstream Profile Descriptor (DPD) messages, respectively.

The CMTS transmits the OCD message on the Physical Link Channel (PLC)and Profile A. The CMTS transmits the DPD message for each profile itsupports on Profile A of the OFDM channel. The CMTS also transmits theDPD for Profile A on the PLC. There is also a dedicated profile for theNext Codeword Pointer (NCP). The NCP profile indicates which subcarriersare usable for NCP and which modulation on each subcarrier is to beused. For CM and CMTS profile support, the latency incurred by thecodeword builder of the MAC-PHY Convergence Layer increases as thenumber of profiles supported by the CMTS increases on this channel, andas the OFDM channel bandwidth decreases. As such, the number of profilessupported by the CMTS can be defined according to the latency budgets atthe codeword builder, as well as the available bandwidth for an OFDMchannel.

FIG. 11 illustrates an example table 110 associated with codewordbuilder latency in accordance with one embodiment of the presentdisclosure. The CMTS can support at least four profiles per CM incertain embodiments of the present disclosure. The CMTS can support atleast four profiles for a 24 MHz OFDM channel with the codeword maximumlatency targets that are provided. For example, the CMTS can supportsixteen profiles for a 192 MHz OFDM channel with the codeword maximumlatency targets defined.

In operation, the CMTS can assign a transition profile in order to testthe ability of a CM to receive a new set of profile parameters for anOFDM channel. A transition profile assigned to a CM is not used by theCMTS to send downstream (DS) traffic to that modem. The CM can reportits reception conditions of the transition profiles to the CMTS usingany suitable protocol. The CMTS can use the transition profile in avariety of ways. For example, based on the values reported, the CMTS candecide to assign additional profiles to a CM after registration, orchange the definition of an existing profile.

In accordance with one example configuration, the CM can support atleast four profiles and a transition profile for each OFDM channel.After CM registration, the CMTS uses any DS profile assigned to the CMto send downstream traffic. The CM can forward traffic received on allof its assigned DS profiles. The CM should not forward DS traffic sentover the profiles it is not assigned to receive. For changes to theprofiles, changes to operating conditions can occur due to changes inthe PHY characteristics of the HFC network, CMs leaving or joining thenetwork, or as a result of administrative controls, etc. The CMTS canreact to these changes by changing the DS profiles.

For service flow to profile mapping, for a bonded downstream serviceflow, the CMTS can transmit the packets belonging to that service flowon more than one channel. For bonded downstream service flows, the CMcan perform the resequencing operations across the different channelsand does not resequence over multiple profiles within the same OFDMchannel. The CMTS can transmit the packets of a downstream service flowon a single profile in an OFDM channel.

Hence, the framework of the present disclosure has the capability tohave multiple downstream modulation profiles. The CMTS could have theability to test and measure the receive capability of each CM and assignit to one of those modulation profiles. In the case of provisioning fourdownstream profiles, the first profile might be predominantly 256-QAM.This profile would be used for initializing CMs, sending MAC ManagementMessages, and carrying data for CMs with lower downstream carrier tonoise ratios. 1024-QAM, 2048-QAM, and 4096-QAM could dominate theremaining three profiles respectively and be used for CMs that are onprogressively better areas of the HFC plant. It is worth noting that,unlike wireless environments such as LTE or WiFi, each CM does not needits own profile. This is because the HFC plant is generally stable andwell-engineered. Thus, with just a few modulation profiles, DOCSIS 3.1is able to balance simplicity and cost with the ability to get themaximum performance out of the HFC plant.

The CMTS could have more total profiles than each CM in certainembodiments of the present disclosure. The HFC plant can have at leastan 8 dB variation in CNR across the HFC plant. This variation can permitdifferent modulations to be used on different locations. CMs could bearranged in a finite number of groups, each with its own modulationprofile in certain embodiments of the present disclosure. Multipledownstream profiles could enable operators to leverage SNR variation toimprove system capacity

FIG. 12 is a simplified block diagram 120 that reflects the codeword andprofile relationship in accordance with one embodiment of the presentdisclosure. Each profile can have a particular CM membership group. On agiven HFC plant, CMs may be able to receive one or more profiles.Profile A could be common to CMs and contain MMM. Profiles B-D could behigher in modulation and serve a particular CM group. The CMTS canmanage these multiple paths. Packets are associated with a profile on achannel based upon forwarding rules. Rules consider CM membership andpacket type (unicast, multicast, MMM, ARP). A Service Flow can propagatealong one path in accordance with one embodiment of the presentdisclosure.

For profile management, from the perspective of the CM, the CM reportmodulation error ratio (MER)/contrast-to-noise ratio (CNR) and receivepower of each sub-carrier. The CM can test its ability to receive unusedprofiles and report the result. For the CMTS, the CMTS updates andpublishes profiles. The CMTS can assign CMs to particular profiles. ForStatic Profiles, a single profile could be the same modulation. Due todownstream time and frequency interleaving, this can performsufficiently well. For Dynamic Profiles, these can be measured,modified, and appropriately sorted. If one CM has a problem, it wouldmove to a new profile. If 100 CMs encounter problems, the profile can besuitably updated.

FIG. 13 is a simplified block diagram 130 that reflects one possibleconfiguration for the downstream (DS) framework in accordance with oneembodiment of the present disclosure. For the DS Convergence Layer, theNCP can point to codewords containing DOCSIS frames. The PLC can providetimestamp, energy management, and boot info for CMs. The DLS can allowCM low power mode and the DTP allows IEEE-1588v2 integration. Thedownstream includes a PHY layer with OFDM and LDPC. It also offersoptions for new spectrum usage. Additionally, it can cost-effectivelyscale to approximately 10+Gbps in the downstream path and approximately2.5+Gbps in the upstream path in certain embodiments of the presentdisclosure.

FIG. 14 is a simplified block diagram 140 that reflects one possiblemapping configuration for mapping packets to FEC blocks in accordancewith one embodiment of the present disclosure. In LDPC, shortenedcodewords take more processing time in the receiver than fully formedcodewords. Packets can be split across codewords belonging to the sameprofile. A shortened codeword should be used if there are not enoughdata bytes to fill one long codeword within the latency budget. For theCMTS, the # total bytes can be provided as (header+payload+parity) anddoes not exceed 2025 bytes in certain embodiments of the presentdisclosure. If (total bytes=odd), then this is sent to the FEC engine.If (total bytes=even), then one 0xFF pad byte is added after the lastPDU and sent to a suitable FEC engine, processor, etc. A CMTS symbolmapper can add trailing bits to map a codeword to a symbol boundary. Forthe CM, the CM extracts total bits between two NCP pointers. In certaincases, if the total bits >16200, the system can use initial 16200 bits.If the total bits=16200, a full codeword is declared. If the total bits<16200, the system can discard [(total bits+8) Modulo 16] bits. Analgorithm can allow the CMTS symbol mapper to add bits at the end of thecodeword, and the CM to remove those bits before doing a FEC decode incertain embodiments of the present disclosure.

For the CMTS, the CMTS systematically builds codewords (regular codewordis 2025 bytes). For example, if the (total bytes=2024), add one 0xFFpadding byte to the payload. If the (total bytes=2023), the system canadd two 0xFF padding bytes to the payload. One 0xFF byte could be addedafter the end of a PDU. If the (total bytes <2023), then shortened lastcodewords are created to be an even number of bytes (max=2022, min=250,for FEC 8/9). For the CM, the CM can extract bits between two NCPpointers. If the bits >16200, the system can discard trailing bits up tothe end of the current sub-carrier. If the bits=16200 (2025 bytes), afull codeword is declared. If the bits <16200, bits are rounded down toa 16 bit boundary (e.g., a two-byte boundary).

FIG. 15 illustrates an example schematic 150 associated with a pluralityof DOCSIS frames and the FEC in accordance with one embodiment of thepresent disclosure. This view is prior to interleaving, where thepackets can be mapped to FEC codewords. FEC codewords are mapped acrosssub-carriers, one symbol at a time and this can create a serial bitstream. The profile associated with the CM group can determine thesub-carrier bit loading. Codewords can start on a sub-carrier boundary.The dots of FIG. 15 represent the intersection of a symbol (vertical)and a subcarrier (horizontal). Codewords are mapped “vertically” acrosssubcarriers (horizontal), one symbol (vertical) at a time. This cancreate a serial bit stream in accordance with example embodiments of thepresent disclosure. Codewords can start on a sub-carrier boundary.Shortened codewords could become more sensitive to frequency-based noiseinterference. This can be mitigated with frequency interleaving incertain environments of the present disclosure.

FIG. 16 illustrates an example schematic 160 associated withtime-frequency scheduling in accordance with one embodiment of thepresent disclosure. Profiles can span one or more codewords in certainembodiments of the present disclosure. Profiles can occur in any orderor combination. In one particular example, the target max delay time forany one profile is 200 us. Packets are placed into FEC codewords andeach codeword is associated with a profile (A, B, C, D). Codewords canbe suitably multiplexed. Profiles can occur in any order or combinationand for multiple channels, 5 OFDM channels can fill the new downstreamspectrum. Channels are independent and each profile can be different ineach channel (e.g., 54 MHz/42 MHz=1.286, 258 MHz=204 MHz×1.265).

The aggregate OFDM channel capacity can change when profiles areupdated. This is a slow and small change. As packet distribution acrossprofile changes, this is a fast and large change. If profiles vary overfrequency, then the start/end locations impact throughput. This can bean error factor. DOCSIS rate-shaping software can perform on-goingchannel estimation. For the interleaver, codeword bits are interleavedacross sub-carriers with a deterministic pattern. Symbols can betime-interleaved per sub-carrier. In summary, the MAC can rate-shapepackets and provide an appropriate quality of service (QoS). Packets canbe placed into FEC codewords. Each FEC codeword is associated with aprofile and profiles describe the downstream modulations that each groupof CMs use. The symbol builder in the convergence layer is allowed toreorder packets to make the PHY more efficient.

FIG. 17 illustrates an example schematic 170 associated with OFDMchannel components in accordance with one embodiment of the presentdisclosure. The OFDM channel can include the data channel (user data andMAC Management Messages (MMM)). The NCP channel can identify codewordsand profiles. The PHY Link Channel (PLC) is located in the downstreamconvergence layer in certain example embodiments of the presentdisclosure. It is used for several tasks including timestamp, energymanagement, and as a message channel for bringing new CMs on line. ThePLC offers CM initialization and control. The NCP channel and the datachannel share the same time and frequency interleaver. The PLC channelis not necessarily interleaved in example configurations of the presentdisclosure. The PLC channel has a preamble and the data channel does nothave a preamble in certain embodiments of the present disclosure.

The CMTS can assign a unique PLC to each OFDM channel. If there is morethan one OFDM channel, the CM can be directed as to which PLC would bethe primary PLC for the CM. When the CM initializes, it first locates aPLC channel. It then acquires just enough configuration information tojoin a primary downstream profile in the main OFDM channel. From there,it receives further configuration information. In general, data isprovided in FEC codewords and the NCP points to codewords. The PLC canbe used for booting CMs. The NCP can be interleaved with the data acrossthe entire channel in example embodiments of the present disclosure.

FIG. 18 illustrates an example schematic 180 associated with an examplemessage block in accordance with one embodiment of the presentdisclosure. The message block (MB) is a building block of the D3.1 PLC.The MB can be cascaded and the message header can be 1 byte in certainexample embodiments of the present disclosure. It can contain a typefield and a small parameter field. The message body can include variablebytes. The parameter field includes the FEC parity, and the type andlength of FEC depends on the MB type.

FIGS. 19-20 illustrates example configurations and packet formatting(190 and 200) associated with an example PLC in accordance with oneembodiment of the present disclosure. A PLC frame could be 8, 16, or 32carriers wide with one, two, or four codewords plus a preamble. Incertain example embodiments, TS may not be in every frame. If the TS ispresent, it can be the first MB after the preamble. The EM may not be inevery frame in certain cases. There can be multiple EMs per-frame. EMscan be generally after the TS (if present) or after the preamble if theTS is not present.

In certain embodiments, there is a preamble of 8 symbols at thebeginning of a PLC frame that consists of a field of fixed pilots. Thereis no separate preamble for the OFDM data channel. The CM can search forthe preamble and the adjacent pilots to lock onto the PLC. The dataportion of the PLC consists of self-contained message blocks. Ingeneral, they are can be three types of message blocks:

Timestamp Message Block (TS MB);

Energy Management Message Block (EM MB); and

Message Channel Message Block (MC MB).

Each message block can have a one one-byte header that consists of atype field, followed by configuration bits, followed by a data field.The timestamp and energy management message blocks can include a cyclicredundancy check (CRC) (e.g., CRC-24-D). The CRC for the message channelis included on the packets within the message channel rather than on themessage block structure itself. The message blocks are then mapped intoa shared set of consecutive FEC codewords. Thus, the contents of the TSand EM message blocks can be slightly delayed by the FEC codeword sizeand how that FEC codeword is mapped to the underlying symbols.

FIG. 21 illustrates an example schematic 210 associated with NCP mappingin accordance with one embodiment of the present disclosure. The NCPchannel is separate from the PLC and does not have to be adjacent to thePLC. In certain example embodiments, there is no preamble in the NCPchannel. Each NCP block has its own FEC. This allows quick use andallows for chaining. NCP blocks and FEC blocks build towards each otherto allow a variable number of NPP blocks.

FIG. 22 illustrates an example schematic 220 associated with an NCPmessage block in accordance with one embodiment of the presentdisclosure. In this example, there is a profile ID, a “Z” bit for zerobit loading, a “C” bit for Profile Change, an “N” bit for NCP Update, an“L” bit for last NCP in symbol, and a “T” bit for directed testing.Hence, the PLC has four fundamental elements in this exampleconfiguration:

Preamble: Initial CM Sync;

TS: Timestamp;

EM: Energy Management; and

MC: Message Channel (for CM initialization).

These elements can be assigned to message blocks, which can be sized,linked, and multiplexed as needed. A fifth function is the codewordpointers that are located in a separate NCP channel. Operational MMM canbe located on a standard profile such as profile A.

FIG. 23 illustrates an example schematic 230 associated with a timestampmessage block in accordance with one embodiment of the presentdisclosure. The timestamp MB can include the eight-byte DOCSIStimestamp. The TS MB can be the first MB after the preamble. The TS MBcan appear in each PLC frame. The timestamp references the end of thelast symbol of the preamble at the start of the PLC frame that caninclude the timestamp. The CMTS can locate the timestamp MB directlyafter the preamble on a primary-capable PLC. The CMTS can transmit thetimestamp MB once in every PLC frame on a primary-capable PLC. The CMTSshould not transmit the timestamp MB on a non-primary-capable PLC.

The TS MB can provide the D3.1 timestamp. The intended allocation of thebytes is: 4 extra EPOCH upper bytes, 4 middle bytes similar to DOCSIS3.0, and 1 extra lower byte for additional precision in accordance withcertain example embodiments. For energy management and sleep-modeoperations, for the CMTS, the CM does not have to continuously listen tothe control channel. The CMTS can allow the CM to move into an off-statethat cannot be directly woken up. The CM can accept a sleep-timermessage and can wake up when told. The sleep timer duration can be setby the CMTS. Typical values could be 10 to 200 ms, or any other suitablevalue, which may be based on particular needs.

FIG. 24 illustrates an example formatting associated with an extendedtimestamp 240 in accordance with one embodiment of the presentdisclosure. In general terms, the extended timestamp can be located onprimary downstream channels. In one example embodiment, a 64-bittimestamp is used. The value of the timestamp can be referenced to theend of the PLC preamble. The extended timestamp has two additionalfeatures when compared to the original DOCSIS timestamp. First, theextended timestamp is now an absolute timestamp rather than a relativetimestamp. Second, the extended timestamp has a higher degree ofprecision in certain example embodiments of the present disclosure.

The extended timestamp can include the concept of Epoch. Epoch refers toa point in time where the timestamp begins to count. The DOCSIS extendedtimestamp can use the same start time as IEEE 1588-2008, which isMidnight, Jan. 1, 1970. The DOCSIS extended timestamp uses the samemethod for counting as IEEE 1588-2008. This method is known asInternational Atomic Time (TAI). TAI moves forward monotonically anddoes not adjust for leap seconds. This differs from protocols such asUnix time that are adjusted for leap seconds.

There are 4 additional lower bits that allow either a higher clockresolution or the ability to communicate phase information within the204.8 MHz clock. In a standalone CMTS system, these bits may be set tozero. In a system where the CMTS is synchronized to a network clock,these lower four bits may represent the phase of the network clock withrespect to the DOCSIS clock. The next five bits of the DOCSIS extendedtimestamp can be used to divide the 204.8 MHz clock by 20 to produce a10.24 MHz clock. These five bits are constructed such that the fieldcould count from a value of 0b00000 to 0b10011 and then reset to0b00000. The 10.24 MHz clock is then used to drive the remaining higherorder bits. These bits include a 32-bit field that is compatible withthe regular DOCSIS four-byte timestamp. The highest 23 bits extend thetimestamp to a count high enough that the timestamp can be referenced toa known point in time.

FIG. 25 illustrates an example formatting 250 associated with an energymanagement message block in accordance with one embodiment of thepresent disclosure. The EM block can set a sleep timer to wake up agroup of CMs. The energy management message block (EM MB) can includemessages that manage the DOCSIS Light Sleep (DLS) Mode, as discussedherein. The EM MB can include one or more entries, where each entry isassociated with an EM group. The EM ID identifies a CM or a group of CMsand the EM ID can be assigned a point in the future, where the CM(s) areto wake up and listen to the PLC channel for a new EM message. The CMTSmay put either zero or one EM MBs into the PLC frame. In one embodiment,the CMTS would not place an EM MB on a non-primary-capable PLC. If theEM MB is included, the CMTS can locate the EM MB directly after the TSMB. For the wake time reference field in the EM MB, the CMTS can pointto the Timestamp Reference Point of the future PLC frame that caninclude the next EM MB that is to be received by the CMs in thecorresponding DLS Group.

FIG. 26 illustrates an example formatting 260 associated with a messagechannel message block in accordance with one embodiment of the presentdisclosure. The MC MB provides an Ethernet channel for specific MMM.There is no FEC in the MC MB as FEC is provided by the PLC frame. Themessage channel connects the CMTS MAC to the CM MAC. The contents of themessage block contain properly formatted DOCSIS MAC Management Messages.The CMTS can transmit the Message Channel MB as the last MB in the PLCFrame. This infers that the message channel MB starts after the energymanagement MB, if present, or the timestamp MB if the energy managementMB is not present. The message channel MB continues to the end of theframe. The MMM messages are segmented across successive message blocks.If the CMTS has no messages to send in the MC, the CMTS can fill the MCMB with the specified idle pattern. Packets can be sent back to backwithout an idle pattern in between them.

FIG. 27 illustrates an example formatting 270 associated with a nextcodeword pointer message block in accordance with one embodiment of thepresent disclosure. NCP MB points to the start of a codeword with aparticular profile within the same symbol. There is at least one NCP persymbol in a particular embodiment of the present disclosure. Fields canremain valid if there is no start pointer in accordance with oneembodiment.

FIG. 28 illustrates an example configuration 280 associated with DOCSISLight Sleep (DLS) Group Mode in accordance with one embodiment of thepresent disclosure. CMs with low traffic can be moved into a DLS Group.There is one DLS group per profile in a particular example embodiment.CMTS stores packets for a group, while CMs are in EM mode. CMTS wakes upthe DLS group and sends the held packets. A CM can sleep for anyconfigurable time interval (e.g., about 200 ms). CMs respond to trafficif necessary and idle CMs can return to the EM mode.

FIG. 29 illustrates an example formatting 290 associated with an energymanagement (EM) duty cycle approach for PLC in accordance with oneembodiment of the present disclosure. A duty cycle can be applied to thePLC. The EM has its own FEC so the rest of the larger codeword does nothave to be received. The EM can include a sleep-timer message. The PLCframe time is constant and periodic in accordance with one embodiment ofthe present disclosure.

FIG. 30 illustrates an example formatting 300 associated with a dutycycle approach for the data channel in accordance with one embodiment ofthe present disclosure. The CMTS can “duty-cycle” CMs in any appropriatemanner. For example: 4 ms on, 196 ms off (2% duty cycle). This candeliver low traffic in bursts. CMs with traffic below a certainthreshold can be placed in the DLS. CM hardware or software can bedesigned to reduce power. In one example embodiment, for the EM States,EM State 0-CM is completely asleep, EM State 1-CM looks at EM block inPLC channel, EM State 2-CM move to data channel and checks for DS databut is still in DLS, EM State 3-CM decides to remain on data channel andexits DLS.

For the PLC message channel, the OFDM Channel Descriptor (OCD) caninclude static variables that require a reboot to change, cyclic prefix,roll-off, subcarrier 0 freq, interleaver depth, a list/range/vector forexcluded SC, pilots, PLC location. For the Downstream Profile Descriptor(DPD), this can include dynamic variables that change on the fly, aprofile DPD and NCP DPD, and a list/range/vector for bit loading. AnOFDM Channel Descriptor can allow the CMTS to communicate the parametersof the downstream OFDM channel to cable modems. OCD describes thedownstream direction. OCD can be used for parameters that are common forall profiles and are static assignments.

FIG. 31 illustrates an example formatting 310 associated with an OFDMchannel descriptor in accordance with one embodiment of the presentdisclosure. A CMTS can generate the OCD message in a format, includingparameters, as identified below. First, a Downstream Channel ID: anidentifier of the downstream channel for which profile is described.This can be an 8-bit field and this ID is part of the same number spaceused for SC-QAM channels. The CMTS can transmit the OCD message on thePLC associated with the downstream channel. The CMTS should not transmitthe OCD message on other PLC channels. The CMTS may transmit the OCDmessage from one OFDM channel on the data channels of other OFDMchannels. The CM can tell the downstream channel ID of an OFDM channelby looking at the downstream channel ID of the OCD message on the PLCchannel.

Second, a Configuration Change Count: a parameter that identifies thegeneration of current generation of a OFDM channel descriptor. The CMTSincrements this field by 1 (modulo the field size) whenever any of thevalues in this message change relative to the values in the previous OCDmessage sent on this downstream channel. The Configuration Change Countmay be referenced in other messages. Again, this is an 8-bit field. TheCMTS should not change any parameters in the OCD message while thechannel is in service. The CMTS can observe the OCD/DPD PLC interval forthe transmission of OCD messages on the PLC channel. The CMTS canobserve the OCD/DPD Profile A interval for the transmission of OCDmessages on the Profile A of the OFDM channel. The role of subcarrierassignment is shared between the OCD and DPD message. The sub-carrierassignment TLV for OCD can define exclusion of subcarriers, location ofthe PLC, and continuous pilots. The DPD allows the CMTS to communicatethe parameters of downstream profiles to the cable modems. There is oneDPD message per profile. DPD is used for parameters that could be uniqueto a profile and are dynamic assignments.

FIG. 32 illustrates an example formatting 320 associated with adownstream profile descriptor in accordance with one embodiment of thepresent disclosure. A CMTS can generate the DPD message, including thefollowing parameters. First, the Downstream Channel ID: an identifier ofthe downstream channel for which profile is described. This is an 8-bitfield and this ID is part of the same number space used for SC-QAMchannels. Second, the Profile Identifier: a parameter that identifiesthe profile described by this message. Profile Identifiers 0 through 15are used for the maximum 16 CMTS profiles. Profile Identifier 0 iscommonly referred to as Profile A. Profile Identifiers 1, 2, and 3 arecommonly referred to as Profiles B, C, and D. Profiles Identifier 16through 254 can be reserved. Profile Identifier 255 is the NCP profile.

Third, the Configuration Change Count: a parameter that identifies thecurrent generation of a profile. The CMTS increments this field by 1(modulo the field size) whenever any of the values in this messagechange relative to the values in the previous DPD message sent on thisdownstream channel. Configuration Change Count may be referenced inother messages. The least significant bit of the Configuration ChangeCount is carried in the NCP (even/odd bit). This is also an 8-bit fieldin accordance with one embodiment of the present disclosure.

The CMTS can publish a next-active profile at least the value “ProfileAdvance Time” before the odd/even bit for either the data profile updateor the NCP profile update is toggled in the NCP message block header.Other parameters of the DPD message are coded as TLV tuples. On profileA of each OFDM channel, the CMTS can periodically transmit DPD messagesfor each profile of that channel. The CMTS can transmit DPD messagesdescribing profile A of an OFDM Channel on the PLC associated with thatOFDM channel.

The CMTS can observe the OCD/DPD PLC interval for the transmission ofDPD messages on the PLC channel. The CMTS can observe the OCD/DPDProfile A Interval for the transmission of DPD messages on Profile A ofOFDM channel. DPD can be used for dynamic assignments of subcarriers.The subcarrier assignment TLV for OCD can define (for both data fieldsand NCP fields) unused subcarriers (Muting) and modulation (Active).

DPD can also be used to specify an NCP profile. The NCP profileindicates what modulation each subcarrier should use if it gets selectedto carry bits from the NCP message block. If the subcarrier should notbe used for NCP, it is marked as muted. The CMTS can use QPSK, 16-QAM or64-QAM for the NCP field. The CMTS can use the same modulation for allsubcarriers in the NCP field. Alternatively, the CMTS may use differentmodulations for each subcarrier within the NCP profile. To allow for acommon implementation, the subcarrier assignment TLV for OCD and DPD canuse a common number space for the TLV type and value assignments.

In summary, CMs in sleep mode can look at the control channel on aperiodic basis to look for sleep timer messages. There can be a 10% dutycycle applied to the PLC channel and a 5% duty cycle applied to the datachannel (e.g., 10 ms on, 50 to 200 ms off). When there is a wake-upmessage, the CM then loops for NPP pointers in the data channel. CMimplementations have a choice of building an optimized narrowband tuneror reusing the wideband tuner.

For the CM boot procedure, the CM can find a convergence layer controlchannel (CLCC) by searching a known set of frequencies. The CM uses theCLCC preamble to determine RF parameters and to decode the CLCC. TheCLCC can include configuration information for the OFDM channel(s)including the boot profile. The CM connects to the boot slice (withprofile A by convention). The CM can then be promoted to a workingprofile, while continuing to listen to profile A for MMM.

FIG. 33 is a table 330 illustrating potential results and profilesassociated with multicast traffic in accordance with one embodiment ofthe present disclosure. Multicast sessions are provided on a profilecommon to the multicast group in accordance with one embodiment of thepresent disclosure. This can depend on how many active profiles a CM cansupport. If channel bandwidth is high and multicast usage is low, thisis less relevant. If channel bandwidth is low and multicast usage ishigh, this issue can become relevant.

For the DOCSIS Time Protocol (DTP), one objective would be to providenative support of IEEE1588 and other external timing protocols. Theapplications can include small cell backhaul (e.g., pico, femto, andmacrocells over DOCSIS) and any other service needing timing. The systemcan provide precise frequency and time to an external system that isconnected to the network port of a DOCSIS CM. Running timing protocolsover the top of DOCSIS adds a timing error due to upstream schedulingjitter and asymmetrical delay. DTP allows conversion to and from othertiming protocols in accordance with one example embodiment.

FIG. 34 is a simplified block diagram illustrating one potential timingconfiguration 340 associated with the CMTS and the CM in accordance withone embodiment of the present disclosure. The CMTS can synchronizeDOCSIS to a network source (e.g., DTI, IEEE-1588v2, etc.). DTP managesDOCSIS latency and asymmetry. The CM generates precision timing usingDOCSIS timing. Accuracy is dependent upon accurate modeling of the CMTS,the CM, and the HFC plant. The system can target accuracy of better thana few μseconds in certain embodiments of the present disclosure.

For using multiple profiles, in practical terms, if the HFC plant cannotbe uniformly upgraded, then having multiple downstream slices can easeCM and HFC plant management, as well as provide more overall throughput.In at least one general sense, it is easier to downgrade than upgrade.Downgrading a profile is safer, as it can make CMs operational.Upgrading a profile is risky as it can cause CMs to fail. A singlechannel profile would likely degrade over time. The decision to sort iseasier than the decision to deny or degrade. With a multi-slice system,less fortunate CMs can be moved to a lower throughput channel withoutdisturbing the rest of the CMs. With a single-slice system, lessfortunate CMs may be denied D3.1 service. This can create serviceissues.

There is somewhat of an OFDM paradox in that a single-slice system worksby providing the worst service to all CMs. When one CM has a channelproblem, the impact of that problem is directly felt by all other CMs. Amulti-slice system works by providing the best overall service to allCMs. When one CM has a problem, it does not directly impact theremaining CMs.

Returning to the architecture of FIG. 1, a brief discussion is providedabout some of the possible infrastructure that may be included incommunication system 10. In one particular instance, communicationsystem 10 can be associated with a service provider digital subscriberline (DSL) deployment. In other examples, communication system 10 wouldbe equally applicable to other communication environments, such as asimple wide area network (WAN) deployment, cable scenarios, broadbandgenerally, fixed wireless instances, and fiber to the x (FTTx), which isa generic term for any broadband network architecture that uses opticalfiber in last-mile architectures. Communication system 10 may include aconfiguration capable of transmission control protocol/internet protocol(TCP/IP) communications for the transmission and/or reception of packetsin a network. Communication system 10 may also operate in conjunctionwith a user datagram protocol/IP (UDP/IP) or any other suitableprotocol, where appropriate and based on particular needs.

The networks discussed herein represent a series of points or nodes ofinterconnected communication paths for receiving and transmittingpackets of information that propagate through communication system 10.The network offers a communicative interface between sources and/orhosts, and may be any LAN, wireless local area network (WLAN),metropolitan area network (MAN), Intranet, Extranet, WAN, virtualprivate network (VPN), or any other appropriate architecture or systemthat facilitates communications in a network environment using networkelements.

CPEs 15 a-15 d can be associated with clients, customers, or end userswishing to initiate a communication in communication system 10 via somenetwork. The term ‘CPE’ is inclusive of devices used to initiate acommunication such as a receiver, a computer, a set-top box, a smarttelevision, an Internet radio device (IRD), a cell phone, a telephone, arouter, a switch, a residential gateway (RG), a fixed mobile convergenceproduct, a home networking adaptor, an internet access gateway, asmartphone (e.g., a Google Droid™, an iPhone™), a tablet (e.g., aniPad™), a personal digital assistant (PDA), or any other device,component, element, or object capable of initiating voice, audio, video,media, or data exchanges within communication system 10. CPEs 15 a-15 dmay also be inclusive of a suitable interface to the human user, such asa display, a keyboard, a touchpad, a remote control, or other terminalequipment. CPEs 15 a-15 d may also be any device that seeks to initiatea communication on behalf of another entity or element, such as aprogram, a database, or any other component, device, element, or objectcapable of initiating an exchange within communication system 10. Inaddition, CPEs 15 a-15 d may be any devices that a service provider maydeploy within the service provider's own network premises. Data, as usedherein in this document, refers to any type of numeric, voice, video,media, or script data, or any type of source or object code, or anyother suitable information in any appropriate format that may becommunicated from one point to another.

CMTS 16 and CMs 20 a-20 b are network elements (apparatuses) that canfacilitate the network communication activities discussed herein. Asused herein in this Specification, the term ‘network element’ is meantto encompass routers, switches, cable boxes, gateways, bridges,loadbalancers, cable CMTS routers, DSLAMs, cellular accessconcentrators, WiMAX access concentrators, firewalls, inline servicenodes, proxies, servers, processors, modules, or any other suitabledevice, component, element, proprietary appliance, or object operable toexchange information in a network environment. These network elementsmay include any suitable hardware, software, components, modules,interfaces, or objects that facilitate the operations thereof. This maybe inclusive of appropriate algorithms, communication protocols, andinterfaces that allow for the effective exchange of data or information.

In one implementation, CMTS 16 and/or CMs 20 a-20 b include software toachieve (or to foster) the network communication activities discussedherein. This could include, for example, the implementation of instancesof a sleep mode module, a message block module, and a profile managementmodule as shown in FIG. 3, where these modules interact, performreciprocating functions, and/or suitably coordinate their activitieswith peer CMTSs across the network. Additionally, each of these elementscan have an internal structure (e.g., a processor, a memory element,etc.) to facilitate any of the operations described herein. In otherembodiments, these network communication activities may be executedexternally to these elements, or included in some other network elementto achieve the intended functionality. Alternatively, CMTS 16 and/or CMs20 a-20 b may include software (or reciprocating software) that cancoordinate with other network elements in order to achieve the networkcommunication activities described herein. In still other embodiments,one or several devices (e.g., servers) may include any suitablealgorithms, hardware, software, components, modules, interfaces, orobjects that facilitate the operations discussed herein with respect toenergy management, message block generation, and profile managementactivities.

Note that in certain example implementations, the functions outlinedherein may be implemented in logic encoded in one or more non-transitorymedia (e.g., embedded logic provided in an application specificintegrated circuit [ASIC], digital signal processor [DSP] instructions,software [potentially inclusive of object code and source code] to beexecuted by a processor, or other similar machine, etc.). In some ofthese instances, a memory [as shown in FIG. 3] can store data used forthe operations described herein. This includes the memory being able tostore instructions (e.g., software, logic, processor instructions, etc.)that can be executed to carry out the activities described in thisSpecification. A processor can execute any type of instructionsassociated with the data to achieve the operations detailed herein inthis Specification. In one example, the processor [as shown in FIG. 3]could transform an element or an article (e.g., data) from one state orthing to another state or thing. In another example, the activitiesoutlined herein may be implemented with fixed logic or programmablelogic (e.g., software/computer instructions executed by a processor) andthe elements identified herein could be some type of a programmableprocessor, programmable digital logic (e.g., a field programmable gatearray [FPGA], an erasable programmable read only memory (EPROM), anelectrically erasable programmable ROM (EEPROM)) or an ASIC thatincludes digital logic, software, code, electronic instructions, or anysuitable combination thereof.

Furthermore, any of the memory items discussed herein (e.g., memoryelement 52, buffers, databases, tables, trees, etc.) should be construedas being encompassed within the broad term ‘memory element.’ Similarly,any of the potential processing elements, modules, and machinesdescribed in this Specification should be construed as being encompassedwithin the broad term ‘processor.’ Each of the network elements can alsoinclude suitable interfaces for receiving, transmitting, and/orotherwise communicating data or information in a network environment.

Note that with the example provided above, as well as numerous otherexamples provided herein, interaction may be described in terms of two,three, or four network elements. However, this has been done forpurposes of clarity and example only. In certain cases, it may be easierto describe one or more of the functionalities of a given set of flowsby only referencing a limited number of network elements. It should beappreciated that communication system 10 (and its teachings) are readilyscalable and can accommodate a large number of components, as well asmore complicated/sophisticated arrangements and configurations.Accordingly, the examples provided should not limit the scope or inhibitthe broad teachings of communication system 10 as potentially applied toa myriad of other architectures.

It is also important to note that the steps in the preceding flowdiagrams illustrate only some of the possible signaling scenarios andpatterns that may be executed by, or within, communication system 10.Some of these steps may be deleted or removed where appropriate, orthese steps may be modified or changed considerably without departingfrom the scope of the present disclosure. In addition, a number of theseoperations have been described as being executed concurrently with, orin parallel to, one or more additional operations. However, the timingof these operations may be altered considerably. The precedingoperational flows have been offered for purposes of example anddiscussion. Substantial flexibility is provided by communication system10 in that any suitable arrangements, chronologies, configurations, andtiming mechanisms may be provided without departing from the teachingsof the present disclosure.

Although the present disclosure has been described in detail withreference to particular arrangements and configurations, these exampleconfigurations and arrangements may be changed significantly withoutdeparting from the scope of the present disclosure. For example,although the present disclosure has been described with reference toparticular communication exchanges involving certain endpoint componentsand certain protocols (e.g., involving various DOCSIS Specifications),communication system 10 may be applicable to other protocols andarrangements, and any version of the DOCSIS Specification. Additionally,communication system 10 may operate with other access concentratorsystems that use different Layer 2 subscriber identifiers. Moreover, thepresent disclosure is equally applicable to various technologies, asidefrom DSL and/or cable architectures, as these have only been offered forpurposes of discussion.

Numerous other changes, substitutions, variations, alterations, andmodifications may be ascertained to one skilled in the art and it isintended that the present disclosure encompass all such changes,substitutions, variations, alterations, and modifications as fallingwithin the scope of the appended claims. In order to assist the UnitedStates Patent and Trademark Office (USPTO) and, additionally, anyreaders of any patent issued on this application in interpreting theclaims appended hereto, Applicant wishes to note that the Applicant: (a)does not intend any of the appended claims to invoke paragraph six (6)of 35 U.S.C. section 112 as it exists on the date of the filing hereofunless the words “means for” or “step for” are specifically used in theparticular claims; and (b) does not intend, by any statement in thespecification, to limit this disclosure in any way that is not otherwisereflected in the appended claims.

1.-21. (canceled)
 22. A method, comprising: mapping packets to forwarderror correction (FEC) codewords at a cable modem termination system(CMTS) in a cable modem network environment, wherein the packets aredestined from the CMTS to one or more cable modems (CMs); mapping theFEC codewords across subcarriers, generating a serial bit stream havingsub-carrier bit loading determined by profiles associated with CMgroups, wherein each profile includes a list of modulation orders forone or more subcarriers within an orthogonal frequency divisionmultiplexing (OFDM) channel; and associating each FEC codeword with arespective one of the profiles, wherein any one profile can beassociated with more than one FEC codeword.
 23. The method of claim 22,wherein each FEC codeword starts on a sub-carrier boundary.
 24. Themethod of claim 22, wherein a symbol mapper at the CMTS adds trailingbits to map the FEC codewords to corresponding subcarrier boundaries.25. The method of claim 22, further comprising splitting the packetsacross a subset of the FEC codewords associated with a common profile.26. The method of claim 22, wherein the CMTS generates the FEC codewordsfrom available bytes corresponding to the packets, wherein each FECcodeword belongs to one of a regular length FEC codeword and a shortenedFEC codeword.
 27. The method of claim 26, wherein the shortened codewordis generated when not enough bytes are available to fill the regularlength FEC codeword within a predetermined latency budget.
 28. Themethod of claim 22, wherein when a total number of bytes of any one FECcodeword is odd, the FEC codeword is sent to a FEC engine, wherein whenthe total number of bytes of the FEC codeword is even, the FEC codewordis modified with addition of a pad byte and the modified codeword issent to the FEC engine.
 29. The method of claim 22, wherein one of theCMs receiving a transmission from the CMTS identifies each FEC codewordfrom bits extracted between two next codeword pointers (NCPs) in thetransmission.
 30. The method of claim 29, wherein when a number of theextracted bits is greater than a predetermined count, the CM uses aninitial number of bits equal to the predetermined count to identify theFEC codeword, wherein when the number of the extracted bits is equal toa predetermined count, the CM identifies the extracted bit with the FECcodeword, wherein when the number of the extracted bits is less than thepredetermined count, the CM discards a specific number of bits from theextracted bits and identifies a remainder of the extracted bits as theFEC codeword.
 31. The method of claim 29, wherein the CM removes anyadditional bits in the FEC codewords added by the CMTS before performinga FEC decode.
 32. Non-transitory tangible computer readable media thatincludes instructions for execution, which when executed by a processorof a cable modem termination system (CMTS) in a cable modem network,performs operations comprising: mapping packets to forward errorcorrection (FEC) codewords, wherein the packets are destined from theCMTS to one or more cable modems (CMs); mapping the FEC codewords acrosssubcarriers, generating a serial bit stream having sub-carrier bitloading determined by profiles associated with CM groups, wherein eachprofile includes a list of modulation orders for one or more subcarrierswithin an orthogonal frequency division multiplexing (OFDM) channel; andassociating each FEC codeword with a respective one of the profiles,wherein any one profile can be associated with more than one FECcodeword.
 33. The media of claim 32, wherein the CMTS generates the FECcodewords from available bytes corresponding to the packets, whereineach FEC codeword belongs to one of a regular length FEC codeword and ashortened FEC codeword.
 34. The media of claim 32, wherein when a totalnumber of bytes of any one FEC codeword is odd, the FEC codeword is sentto a FEC engine, wherein when the total number of bytes of the FECcodeword is even, the FEC codeword is modified with addition of a padbyte and the modified codeword is sent to the FEC engine.
 35. The mediaof claim 32, wherein one of the CMs receiving a transmission from theCMTS identifies each FEC codeword from bits extracted between two nextcodeword pointers (NCPs) in the transmission.
 36. The media of claim 35,wherein when a number of the extracted bits is greater than apredetermined count, the CM uses an initial number of bits equal to thepredetermined count to identify the FEC codeword, wherein when thenumber of the extracted bits is equal to a predetermined count, the CMidentifies the extracted bit with the FEC codeword, wherein when thenumber of the extracted bits is less than the predetermined count, theCM discards a specific number of bits from the extracted bits andidentifies a remainder of the extracted bits as the FEC codeword.
 37. Anapparatus in a cable modem network environment, comprising: a memoryelement for storing data; and a processor, wherein the processorexecutes instructions associated with the data, wherein the processorand the memory element cooperate, such that the apparatus is configuredfor: mapping packets to forward error correction (FEC) codewords,wherein the packets are destined to one or more cable modems (CMs) inthe cable modem network environment; mapping the FEC codewords acrosssubcarriers, generating a serial bit stream having sub-carrier bitloading determined by profiles associated with CM groups, wherein eachprofile includes a list of modulation orders for one or more subcarrierswithin an orthogonal frequency division multiplexing (OFDM) channel; andassociating each FEC codeword with a respective one of the profiles,wherein any one profile can be associated with more than one FECcodeword.
 38. The apparatus of claim 37, wherein the FEC codewords aregenerated from available bytes corresponding to the packets, whereineach FEC codeword belongs to one of a regular length FEC codeword and ashortened FEC codeword.
 39. The apparatus of claim 37, wherein when atotal number of bytes of any one FEC codeword is odd, the FEC codewordis sent to a FEC engine, wherein when the total number of bytes of theFEC codeword is even, the FEC codeword is modified with addition of apad byte and the modified codeword is sent to the FEC engine.
 40. Theapparatus of claim 37, wherein one of the CMs receiving a transmissionfrom a cable modem transmission system (CMTS) in the cable modem networkidentifies each FEC codeword from bits extracted between two nextcodeword pointers (NCPs) in the transmission.
 41. The apparatus of claim40, wherein when a number of the extracted bits is greater than apredetermined count, the CM uses an initial number of bits equal to thepredetermined count to identify the FEC codeword, wherein when thenumber of the extracted bits is equal to a predetermined count, the CMidentifies the extracted bit with the FEC codeword, wherein when thenumber of the extracted bits is less than the predetermined count, theCM discards a specific number of bits from the extracted bits andidentifies a remainder of the extracted bits as the FEC codeword.